1 files changed, 54 insertions, 0 deletions
diff --git a/source/blender/draw/engines/eevee/shaders/bsdf_sampling_lib.glsl b/source/blender/draw/engines/eevee/shaders/bsdf_sampling_lib.glsl
new file mode 100644
index 00000000000..da14a2dfee4
--- /dev/null
+++ b/source/blender/draw/engines/eevee/shaders/bsdf_sampling_lib.glsl
@@ -0,0 +1,54 @@
+
+uniform sampler1D texHammersley;
+uniform sampler2D texJitter;
+uniform float sampleCount;
+uniform float invSampleCount;
+
+vec2 jitternoise = vec2(0.0);
+
+void setup_noise(void)
+{
+	jitternoise = texture(texJitter, gl_FragCoord.xy / NOISE_SIZE, 0).rg; /* Global variable */
+}
+
+vec3 hammersley_3d(float i, float invsamplenbr)
+{
+	vec3 Xi; /* Theta, cos(Phi), sin(Phi) */
+
+	Xi.x = i * invsamplenbr; /* i/samples */
+	Xi.x = fract(Xi.x + jitternoise.x);
+
+	int u = int(mod(i + jitternoise.y * HAMMERSLEY_SIZE, HAMMERSLEY_SIZE));
+
+	Xi.yz = texelFetch(texHammersley, u, 0).rg;
+
+	return Xi;
+}
+
+vec3 hammersley_3d(float i)
+{
+	return hammersley_3d(i, invSampleCount);
+}
+
+/* -------------- BSDFS -------------- */
+
+float pdf_ggx_reflect(float NH, float a2)
+{
+	return NH * a2 / D_ggx_opti(NH, a2);
+}
+
+vec3 sample_ggx(float nsample, float a2, vec3 N, vec3 T, vec3 B)
+{
+	vec3 Xi = hammersley_3d(nsample);
+
+	/* Theta is the aperture angle of the cone */
+	float z = sqrt( (1.0 - Xi.x) / ( 1.0 + a2 * Xi.x - Xi.x ) ); /* cos theta */
+	float r = sqrt( 1.0 - z * z ); /* sin theta */
+	float x = r * Xi.y;
+	float y = r * Xi.z;
+
+	/* Microfacet Normal */
+	vec3 Ht = vec3(x, y, z);
+
+	return tangent_to_world(Ht, N, T, B);
+}